Pivoted breech block locking mechanism



Sept- 9, 1952 B. sAHLlN ETAL 2,609,731

PIVOTED BREECH BLOCK LOCKING MECHANISM Filed May 6, 1948 3 Sheets-Sheet 1 Figi y 72 834 3 7,?36 54 4g?? -W 1r 4' 52 .53 F 9.2. 37 46 5o 5l 49 l l l l l y ,8L

Arr-7.0'

slept. 9, 1952 PIVOTED BREECH BLOCK LOCKING MECHANISM Filed may e, 194e 3 sheets-sheet 2 8' lf 5 9 25 54 @i I 5a a .5:5 4"

Fglh

s a' .57 .fa 49 51 IlI lI l/ a. sAHLlN E-rAL 2,609,73l

SPf 9 1952 B; sAHLlN ETAL 2,609,731

PIVOTED BREECH BLOCK LOCKING MECHANISM Filed May 6, 1948 5 Sheets-Sheet 3 Fg.. 30 H Patented Sept. 9, l952 MECH ` ANISMY Brjer-Sahlin, Stockholm, and Edvin Emanuel' J ansson,` deceased,vv late of-` Bofors,` Swedem. .by Halvar Nyqvist,. executor, 5 Bofors,t Sweden as,- signors to.` Aktiebolaget Bofors Bofors, Sweden, ajoint' stock company of Sweden e i ApplicationJMay.6,1948;seriamaeagma rnzsweden Manenzarais 'Y e'ciaims. (cies-isc) bores' the' mst-mentioned type ofarrangements V- operates too slowly, while the latter' type` involves construotions,.too cumbersome, which do not operate satisfactorily.'

. 1f Ac'c'ording'tointhe-present'h invention, `the problem has been solved by a combination of-said two arrangements-known: perse; inasmuch as the return of the breech and, thus the ejection ofthe' cartridge case and thev storing offenergy-for' the other working operations of the vfirearm is effectedA bythep'owder gases' acting directly on the?bottom"v infthecase, after an unlatching. fork actuatedj by the recoil hasv unlatched'the breech-lock, loosened the case and inpa'rte'd.A 'the' breech andv the. case with a 'certain rearward initial' speed. f

The invention is illustrated in the accompanying drawing, wherein Fig. 1 represents a diagrammatic vertical longitudinal section through a portion of a firearm according to the invention, this figure showing the position of the parts at the moment of firing. Fig. 2 is a detail section on line II-II in Fig. 1. Fig. 3 is a longitudinal detail section showing the position of the parts immediately after the firing moment. Fig. 4 is a detail section on line IV--IV in Fig. 3. Fig. 5 is a longitudinal detail section showing the position of the parts immediately before the termination of the recoiling movement. Fig. 6 is a longitudinal detail section showing the position of the parts during the forward movement of the breech. In the drawing, I designates the barrel of a firearm, said barrelbeing displaceably mounted in a guide sleeve-not shown-and in a recoiling jacket 4 coupled to the guide sleeve, an advancing spring 5 being arranged between said recoiling Jacket and the barrel. Screwed fast to Y the barrel I is a breech guide 6, which is provided with two depending lugs 1, in which anunlatching fork 8 with two fork Shanks 8' is pivoted on a shaft 9, which is retained in itsposition by the sides 4' of the recoiling jacket 4. Fork 'Shanks 8' move between two abutments (not The unlatching forkvmay of course Y shown). be mounted in some other part of the recoiling system.

` The bearing pin of the unlatchingforkflis,

smarranged relatively to any abutment 53 arranged on the4 recoiling-jacketl 4 that adriving arm` 52 on. the unlatching fork. when recoiling will strike against the abutment 53 so `as tov be 'stopped` by said abutment, the, unlatchingjfork beingv thus caused to swingV about `its shaftlS. The rear end of a non-rotatable breech' I2, which is' displaceable in the` longitudinal` direce tion in the casing E against the action lof 'a wardfmovement againsti a `'cushioning-device (not, shown) to be stopped by theylatter.. i

A` striker I6 providedlwith a primingpintt is displaceably"arranged'in the breech', I`2 in jthe 'longitudinal direction, thereof. said" striker' fbegingf actuated. by ajstrikerA spring and` havinga transverse recess 36 adaptedpto receive a' striker bridge 3l, Vwhich; i's' somewhat displaceabl'e, relaitive'ly to' the breech i2 in thejlongitudinal direc'- tion, thereof; Thestrik'er bridge 3l' is displaceable by means oftheslianks 8' oftheunlatch- They striker bridge isl provided with` oblique lcam surfaces 48 cooperating with oblique ycam surfaces 41' onV breechf latches" 46, which are s'wi'ngably'A or displacea'bly arranged inthe-'breech I2, to bring said latches 46 out of engagement with stop abutments 5I arranged in the casing 8.

The mode of operation of the arrangement is as follows, starting from the position of the parts at the moment of firing, as shown in Fig. l. The breech is locked to the tube, While bearing on the rear end of the cartridge introduced into the cartridge chamber, by means of the breech latches 46 and the abutments 5i over the breech guide 6 screwed fast to the barrel I. The striker I6. the priming pin 35 and the striker bridge 31 are in their foremost position, the priming pin havingstruck the percussion cap of the cartridge. On account of the jarring bottom pressure produced at ring, the recoiling system, that is to say the tube with the breech guide and the breech, move rearwardly. At the commencement of the recoiling movement, the driving arm 52 of the unlatching fork 8 hits the abutment 53 of the recoiling jacket 4, so that the unlatching fork 8 is swung about its shaft 9 and thefork shanks 8' thereof move the striker bridge 31 rearwardly, which in turn, at straining of the striker spring 39, moves the striker I6 and the priming pin 35 rearwardly, while releasing with its oblique cam surfaces 4B the engagement between the breechV latches 46 and the abutments 5I, so that the breech is made free and will have a rearward initial movement imparted thereto so as to strain operating springs, not shown. During the continiled rearward movement of the breech. the pressure of the powder gases act on the shell bottom, ywhich in turn vpresses against the'breech and impartsthe continued rearward movement to the same. The recoiling system continues its rearward movement at compression of the advancing spring 5. During the rearward movement of the breech, the feeding of the cartridges takes place in a manner which need not be discussed in this connection.

The invention is not conned to theekample l shown, inasmuch as many alterationsv may be undertaken within the scope of the invention.-l

VFor example,-the unlatching member mayV be adapted to actuate the breech directly after the faces of the said breech latches upon rearward movement of said element. act so as to unlatch said breech latches and thereafter vact vso as te 'impart a krearward initial movement to said breech, :after said breech latches have been unlatched.

2. An automatic firearm according to claim ,1,

i wherein said rearm also includes a striker, and

engagement abutments wherewith said breech latches are pivotally arranged in the breech, wherein the'pivoted unlatching member of said breech unlatchirier mechanism consists of a fork -member, the shanks of said fork being s o disposed as'to'move said element, and wherein said lastunlatching operation. Also, the unlatching. f

member need not necessarily be bifurcated.

Having now describedour invention, what we claim as new and desireto secure by Letters `atentis:

j' l. In an automatic firearm having a short bar rel recoil in the longitudinal direction, said firearm having a recoiling system which includes a lrecoil jacket, a positivelyjclosed breech block, and Vat least two breech latches each provided with an oblique cam surface and arranged` between said breech and said recoiling system for locking or unlocking said breech to said recoiling system, said breechlatches being positioned in an "oblique position in'relation to said longitudinal direction whenvsaidbreech is locked to said recoiling system, breech unlatching mechanism,

which includes, in combination, an abutment positioned on said recoil jacket, a pivot shaft iixed to said recoiling System; a pivoted unlatching member pivoted ori'said pivot shaft, whereby said pivoted unlatching member,v when Asaid rearm is redstrikes .against said abutment stop andis thereby causedto pivot about said shaft;

andan element operatively disposed so as to be moved by said pivoted nlatching memberf-asitV pivotsk about said -shaft said element :being-` -pro'- .vided withVat-least,two'obliquely disposed ,cam

surfacesat its rearward*v end, whereby said cam surfaces, when they strike against the fcamsurnamed element comprises a striker bridge extending transversely through said striker, said striker bridge being displaceable relative to said' breech in the longitudinal direction of said breech, and said striker-bridge further being p rovided .with said oblique cam surfaces cooperating 'with said' obliquefcam surfaces on saidbreech latches whereby, when said cam surfaces-are brought into operative engagementA by movement of said pivoted unlatching member, said breech Matches are swung out of contact with said engagement abutments of saidy firearm. Y

BRJE'SAHLIN. HALVAR NYQVIST,

3o VE'zzre-tiwfor of the Estate of Edwin Emanuel Janssovi,

DeeeaseatA ,y

" REFERENCES CITED The following references aregoffrecordinthfe file of thisv patent:

UNITEn-s'rATEs'PAfrENTs' f" 'I A munter Name v Date v v971,061 Mauser Sept. 27, 1910` 1,o9e,679 vchromev K ay V12, i914 4 u y FOREIGNy vPA'rErrrs' Number Country Y .ljate'fV 132382 Greet Britain o fj19o1 315,615 Germany j N,ov. 10,1919 

